1. Field of the Invention
The present invention relates to an inner-rotor motor.
2. Description of the Related Art
Inner-rotor motors having a large axial dimension and including bearings arranged on both upper and lower sides of an armature have been widely used.
The motors of this type need to have brackets to support the bearings fitted on both upper and lower sides of the armature.
In a motor described in JP-A 11-220860, a fixing screw 7 is passed through a ring-shaped stator 1 in an axial direction, and this fixing screw 7 is used to fasten cover members 5 and 6 to the ring-shaped stator 1.
Meanwhile, in a motor described in JP-A 2001-136699, a metallic part having a high thermal conductivity, such as a screw 9, a rivet 10, a burr 11, is passed through a hole 8 to attach a stator core 13 to a base 16. At this time, a raised portion 17 or an insulator 14, which is made of an insulating material, is arranged between the metallic part and a conducting wire 5 to prevent a contact between the metallic part and the conducting wire 5.
In the case where a screw hole passing through the stator is defined in the stator as in the motor described in JP-A 11-220860, the screw hole may be defined at an outer end of a tooth as in the motor described in JP-A 2001-136699. In this case, the raised portion of the insulator is arranged between a winding and the screw to provide isolation therebetween.
However, in the case where the winding and the screw hole are radially close to each other, the raised portion of the insulator has only a small radial thickness. The small thickness of the raised portion of the insulator results in a decrease in the strength of the raised portion, and the raised portion may be bent radially outward if the winding contacts the raised portion when the winding is formed. If the raised portion is bent radially outward, the raised portion may prevent insertion of a fixing member, such as the screw. Moreover, when the fixing member is inserted through the screw hole, the fixing member may be brought into contact with the raised portion of the insulator to cause damage to the raised portion of the insulator.